The issue involves a set of drill bits carried by the Curiosity rover, which launched Nov. 26 to Mars. When project developers made an internal decision not to send the equipment through a final ultra-cleanliness step, it marked a deviation from the planetary protection plans scripted for the Mars Science Laboratory mission.

That judgment, however, didn't reach NASA's chief protector of the planets until "very late in the game," said Catharine "Cassie" Conley, NASA's planetary protection officer. "They didn't submit the request for the deviation not to comply with their planetary protection plan until several months ago," she emphasized.

Conley told Space.com that the initial plan called for placing all three of the drill bits inside a sterile box. Then, after Curiosity landed, the box would be opened for access to the sterilized bits via the rover's robot arm, extracted one by one and fit onto a drill head as the mission progressed.

But in readying the rover for departure to Mars, the box was opened, with one drill bit affixed to the drill head, Conley said. Also, all of the bits were tested pre-launch to assess their level of organic contamination. While done within a very clean environment, that work strayed from earlier agreed-to protocols, she said.

"That's where the miscommunication happened," Conley said. "I will certainly expect to have a lessons-learned report that will indicate how future projects will not have this same process issue. I'm sure that the Mars exploration program doesn't want to have a similar process issue in the future. We need to make sure we do it right."

Equatorial target
Conley said the deviation from protocol was reinforced by science and project officials concluding that Curiosity's target landing spot, Gale Crater, is free of potentially life-harboring ice — at least at depths that the drill bits would penetrate.

"That reinforced the reasonableness of not having the drill bits sterilized, because there's unlikely to be 'special regions' in the Gale Crater landing site," Conley said.

DLR

The Gale Crater is the target for NASA's Curiosity Mars rover.

The $2.5 billion Mars Science Laboratory mission was designed to comply with a requirement to avoid going to any site on the Red Planet known to have water or water-ice within 3.3 feet (1 meter) of the surface.

Adhering to cleanliness standards is a way to make sure the mission does not transport Earth life to Mars. Doing so preserves the ability to study that world in its natural state and also avoids contamination that would obscure an ability to find native life on that planet, if it exists.

Conley emphasized that the Curiosity assembly team and technicians did an excellent job of keeping Curiosity cleaner than any robot that NASA' s sent to Mars since the Viking lander in the 1970s.

Still, the decision to not keep the drill bits ultra-clean shows the process needs to be fixed, Conley said.

"It would have been better for them to check with me before they opened the box of bits to confirm that it was OK … rather than trying to ask for it afterwards," she said. "In this case it was fine. But for future missions we want to make sure that they ask beforehand."

Science editor Alan Boyle's blog: "Astronaut Abby" is at the controls of a social-media machine that is launching the 15-year-old from Minnesota to Kazakhstan this month for the liftoff of the International Space Station's next crew.

Habitable environments
The Mars Science Laboratory is not a life-detection mission. Rather, it will study whether the Gale Crater area of Mars has evidence of past and present habitable environments.

"Direct life detection is inherently difficult, some would argue currently impossible, because there is no uniform agreement on life," said Scott Hubbard, the former "Mars Czar" for NASA Headquarters in Washington.

Hubbard is now a professor in the Department of Aeronautics and Astronautics at Stanford University in Stanford, Calif., and author of the new book "Exploring Mars — Chronicles from a Decade of Discovery," published by the University of Arizona Press.

"There is no mathematical expression for life as there is gravity … only a series of attributes such as complexity, reproduction, metabolism, responsiveness and so on," Hubbard told Space.com. "We don't have a 'Star Trek' tricorder that says, 'It's alive, Jim.'"

Mars sample return
On-the-spot detection of life is difficult, underscoring the need to return to Earth well-selected samples from the Red Planet for analysis in a lab, Hubbard noted.

There are three reasons for pushing forward on a Mars return sample effort, he said: The best laboratory equipment can be employed, much of which cannot be reduced to spacecraft size; many labs and many scientists can be utilized to cross-check each other with alternate techniques; and discoveries can be followed and rechecked years later with new tools and techniques and hypotheses.

"The treaty-type agreements on planetary protection specify very rigorous levels of cleanliness to prevent forward and backward contamination," Hubbard said. "Spacecraft going to potential habitable zones on Mars must be cleaned to an amazing degree, even sterilized. Samples returned to Earth will be treated as if they were highly infectious until demonstrated otherwise."

Price tag estimates for a "Sample Receiving Facility" here on Earth have ranged as high as $300 million, Hubbard said. "Nevertheless, I think it is all worth it to find out 'Are we alone?'… 'Did life ever arise on Mars?'" he said.

Leonard David has been reporting on the space industry for more than five decades. He is a winner of this year's National Space Club Press Award and a past editor-in-chief of the National Space Society's Ad Astra and Space World magazines. He has written for Space.com since 1999.